Crypticus,
Welcome to the forum, and nice choice
I don't own a UMX radian (I've been itching to get one, but at this rate they'll be discontiuned by the time I get around to it), but they fly so very nice.
I am curious, what more would you like it to do? On only 2 servos, and stabilized ones at that, there's not much more it *could* do. There's nothing on the wings so can't add in flaperons or crow breaks. With the stablization you're prety much fixed on rudder/elevator, so elevons or V-tail conversions are pretty much out, and frankly you probably wouldn't like 'em.
At most I *might* see a throttle/elevator mix to give you a little down on higher throttle so the airframe doesn't climb when powered, but that only makes sense if you want to power cruise. The motor on a power glider is designed for launch -- maximum altitude in the shortest time. Otherwise, the airframe is desinged to fly unpowered, but if you prefer powered flight, it can do it.
I've seen a few mods to the frame to make the wing easier to remove, but that's all I've seen so far.